1. Field of Invention
This invention relates to wireless networks and more particularly to a method and system for a mobile station to identify to a wireless network agent, an access point into a wireless network. The wireless network agent may be a foreign agent or a home agent of the wireless network, for example, and the access point enables the mobile station to communicate over an air interface with an entity in the wireless network.
2. Description of Related Art
Mobile Internet protocol (“mobile IP”) defines mechanisms to allow a mobile station to move between coverage areas of wireless networks without communications with the mobile station being disrupted.
A home network is one of the coverage areas of the wireless network. In the home network, the mobile station operates like a node on the wireless network. The mobile station has a home address that allows packets to be delivered directly to the mobile station. Also, the home network has a home agent. The mobile station registers with the home agent so that, among other functions, the home agent can keep track of whether the mobile station is in the coverage area of the home network.
A visited network is another coverage area of the wireless network. The visited network is a network other than the home network. If the mobile station moves within the coverage area of the visited network, then the mobile station registers with a foreign agent. Among other functions, the foreign agent keeps track of whether the mobile station is in the coverage area of the foreign network. The mobile station also registers with the home agent. By registering with the home agent, the home agent can direct to the visited network any packets having the home address of the mobile station. The mobile station obtains a temporary IP address in the visited network, through dynamic host configuration protocol (DHCP) or any other mechanism. The temporary IP address allows the mobile station to receive packets when attached to the visited network.
The carrier division multiple access (CDMA) architecture defines an exemplary configuration of the home network and the visited network. In the CDMA architecture, the home network and the visited network include a base station and a packet data serving node (PDSN). The base station produces a radiation pattern that defines a coverage area for the visited network and the PDSN provides a packet-based interface into an IP network.
When a traffic channel is assigned to the mobile station and a radio-packet (R-P) link is established between the base station and the PDSN, the mobile station can communicate with the entities in the CDMA architecture. The traffic channel carries packets between the mobile station and the base station and the R-P link carries packets between the base station and the PDSN.
Registration on the Wireless Network
The mobile station will engage in mobile IP registration after establishing the PPP session. The process by which the mobile station engages in mobile IP registration depends on whether the mobile station is in a visited network or in a home network.
(a) Mobile Registration in a Visited Network
If the mobile station is in a visited network, then the mobile station listens for agent advertisement messages from a foreign agent in the wireless network. The agent advertisement messages indicate to the mobile station that a foreign agent is available to serve the mobile station. When a mobile station receives an agent advertisement message, it sends a mobile station registration request to the foreign agent.
The foreign agent will receive the mobile registration request. Then, the foreign agent will send an access request to an authentication, authorization, and accounting (AAA) server. The access request may have a base station identifier (BSID). The BSID uniquely identifies the base station that serves the mobile station. The access request is a request by the foreign agent to authorize the mobile station to register with the foreign agent. The base station provides the BSID to the PDSN when the R-P link is established.
The AAA server will use the BSID of the base station to determine whether to authorize the mobile station to register with the foreign agent. If certain base stations identified by the BSID serve the mobile station, then the AAA server might not allow the mobile station to register with the foreign agent. If other base stations identified by the BSID serve the mobile station, then the AAA server might allow the mobile station to register with the foreign agent. The AAA server may also use the BSID to provide differentiated billing to the mobile station based on the particular base station that serves the mobile station. The wireless network may bill an account for the mobile station at one rate if the base station that serves the mobile station is part of one group of base stations, and bill the account for the mobile station at a second rate if the base station is part of another group of base stations.
The AAA server sends a reply to the access request, indicating whether the mobile station is authorized to register with the foreign agent. Then, the foreign agent may send the registration request to the home agent so that the home agent can determine whether the mobile station is authorized to register with the home agent. Like the foreign agent, the home agent may send an access request to the AAA. In turn, the home agent may receive an access reply to the access request. The access reply may indicate whether the mobile station is authorized to register with the home agent. In this regard, the home agent may provide to the foreign agent an indication of whether the mobile station is authorized to register with the home agent.
If the AAA server refuses to authorize the access requests, then the mobile station is not authorized to register with the foreign agent and/or the home agent. The mobile station cannot communicate over the wireless network. If the AAA server authorizes the access requests, then the mobile station is authorized to register with the foreign agent and the home agent. From this point forward, the home agent may tunnel to the foreign agent packets destined to the mobile station. The foreign agent then delivers them to the mobile station. When the mobile station is originating packets, the mobile station can send them to the foreign agent which then tunnels them to the home agent.
(b) Mobile Registration on a Home Network
When the mobile station is in the home network, the mobile station sends the mobile registration message to a home agent. The mobile station might not have to send a mobile registration message to a foreign agent because the mobile station is already in the home network. The mobile station inserts the address of the home agent into the mobile registration message and sends the mobile registration message to the home agent. The mobile station typically is programmed with the address of the home agent.
The home agent will receive the mobile registration request and send an access request to the AAA server. The access request may have a BSID. The AAA server will use the BSID to determine whether to authorize the mobile station to register with the home agent and/or to provide differentiated billing to the wireless terminal. The AAA server then sends a reply to access request, indicating whether the mobile station is authorized to register with the home agent. In turn, the home agent may provide to the mobile station an indication of whether mobile station is authorized to register with the home agent.
802.11 Protocol Networks In a CDMA network, the AAA server uses the BSID to authorize the mobile station to register with a wireless network agent and provide differentiated billing to the mobile station, for example. In the Institute of Electronics and Electrical Engineers (IEEE) 802.11 et al. protocol, another well known wireless network protocol, the mobile station accesses a wireless network through an access point. The access point is analogous to the base station, but the access point typically serves a geographic area smaller than that served by the base station of the CDMA network. Also, the access point typically provides higher bandwidth communication to the mobile station compared to the base station. Mobile IP call setup in an 802.11 protocol network also involves sending a mobile IP registration request to a wireless network agent and the AAA server authenticating the mobile station to register with the wireless network agent. But because the 802.11 protocol network does not define any mechanism for identifying to the wireless network agent an indication of the access point into the wireless network, the 802.11 protocol network is not arranged to provide similar services available to mobile stations operating in the CDMA architecture.